This application is a continuation-in-part of application No. 06/520,305 filed by Donald C. Erickson on 08/04/83, which is incorporated by reference now U.S. Pat. No. 4,563,295.
There has long been an identified need for solution compositions useful for absorbing substantial amounts of water vapor at high temperature and at high boiling point elevations, but which can use ordinary materials of construction without causing excessive corrosion. This is especially true in absorption cycle processes or apparatus, such as air conditioners or heat pumps--both high temperature, heat powered (forward cycle) and waste heat powered (reverse cycle), absorption heat pumps, and also in drying apparatus for air or other gases.
There are many problems in the prior art practice of regenerative water vapor absorption using a liquid solution. Some absorbents such as LiBr and LiCl beocme excessively corrosive above about 170 degrees C. Others such as the glycols become thermally unstable at high regeneration temperatures, and also have appreciable vapor pressure and are combustible. Prior art West German patent No. 2942697 discloses that a mixture of LiNO.sub.2, LiNO.sub.3, NaNO.sub.2, NaNO.sub.3, KNO.sub.2, KNO.sub.3, and water can be used as a water vapor absorbent, as can the individual components. The alkali metal nitrates are neither corrosive nor thermally unstable at high temperature. However they become unstable when mixed with alkali metal nitrites, and they have other problems when used individually, such as limited range of solubility, limited boiling point elevation, excessively high anhydrous melting point, or limited water carrying capacity.
Further background information can be found in the technical article "A High Temperature Noncorrosive Absorption Working Pair" presented by D. C. Erickson on Mar. 21, 1985 at the Absorption Experts '85 meeting in Paris, France and sponsored by Institut Francais du Petrol, and also in International Publication Number W084/01422.